CDC Plans to Mix and Match H5N1 and Human Genes Again
Recombinomics Commentary
March 23, 2005
>> "It may be that we find out that it's really not as scary a situation as one would think," Dr. Cox says. "Or we may find some gene combinations work well together." Similar CDC experiments using an H5N1 virus from an outbreak in Hong Kong in 1997 didn't produce "sensational" results, she says. Details of that research are still being written up for publication. <<
The scary situation is the CDC repeating experiments, which are conceptually flawed, and then trying to draw a meaningful conclusion. As noted above, swapping H5N1 genes from 1997 with human genes didn't produce any sensational results, and there is little reason to expect a re-run to be any different. The only useful result would be more evidence showing that the much anticipated reassortment between avian and human genes isn't going to happen, and the WHO can stop including the non-occurrence of the non-event in their bird flu press releases.
A quick look at the influenza sequences at GenBank shows that influenza evolves by changing genes, not exchanging genes. Reassortment does not create new genes, it merely puts complete genes in novel environments. It can allow for more dramatic changes due to recombination, which does change genes, and such changes have happened in H5N1. However, these changes are assumed to be due to random mutation, which may happen over long time periods, but they are not the driving force behind rapid evolution. It is recombination that creates the year to year changes that select for new genomes that can survive immunological attacks by the host.
Moreover, as noted in WHO warnings on the pandemic potential of H5N1, the virus has evolved in recent years and has broadened its host range to mammals such as wild and domestic cats, mice, ferrets, and humans. Infections in humans have an extremely high case fatality rate. This evolution involved changing gene sequences and has been done in the absence of the isolation of any human / avian reassortant.
If WHO wants to see what happens when human and avian genes mix together, they can look at the Korean swine that contain human WSN/33 genes and avian H9N2 genes. The six isolates from swine have recombined genes and reassorted genes and these combinations were selected in natural hosts, pigs on farms. Thus, not only have the genes mixed and matched, but they have done so under natural selection pressures.
Remarkably, five months after being notified of the reassorted and recombined genes, WHO still has not been able to prove or disprove the existence of the sequences in pigs on farms in Korea.
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